Grave's disease

Graves’ hyperthyroidism present along with characteristic ocular and orbital manifestations. It is believed that the thyroid gland and ocular adnexa share one or more antigens that are the target of autoreactive T and B lymphocytes and antibodies. The ocular disease manifestations are referred to as thyroid eye disease (TED; also f to as Graves’, or thyroid-associated, ophthalmopathy or orbitopathy).

Epidemiology:
Prevalence Grave's dz 0.5% till 2%
50% will have Thyroid eye disease

Pt may have TED 6 month b4, with or after dz w Grave's

Pt Grave's with TED may hav eu or hypothyroidism state- 10%

Female: male = 5.5, peak at 5th and 7th decade

85-95% bilateral dz, but pt with eu or hypothyroidism more of unilateral dz

Characteristic signs and symptoms of TED:
eyelid retraction (80%),
exophthalmos (62%),
extraocular muscle dysfunction with or without diplopia (43%),
and pain (30%).
Other common complaints include excessive tearing, foreign body sensation, redness of the eyes and eyelids, blurred vision and photophobia.
Severe disease with visual loss from a compressive optic neuropathy was infrequent and was seen in only 6%.

It is believed that the pathological changes outlined previously are initiated by autoreactive T lymphocytes that migrate into the fat, extraocular muscles and other soft tissues of the orbit, and become activated by reacting to autoantigens present in these tissues.[15] The activated T lymphocytes then trigger an inflammatory reaction that involves the release of cytokines, which in turn stimulates the proliferation of fibroblasts, secretion of glycosaminoglycans, expansion of fat cells and inflammation of the extraocular muscles.

The TSH receptor has been identified as a possible autoantigen that is present both in the thyroid gland and in orbital tissues, and which may trigger and sustain the autoimmune response.
Disease is associated with antibodies to the TSH receptor. Other postulated autoantigens include the IGF receptor,extra ocular muscle proteins and thyroglobulin.

Orbital fibroblasts are key cellular components in tissue remodeling in the orbits of patients with TED. They not only participate in the recruitment of cells of the immune system, but are also involved in remodeling of the connective and adipose tissue, and of the extraocular muscles.

The characteristic clinical findings of TED of redness and swelling of the periorbital tissues (including the eyelids, conjunctiva and caruncle) are likely related to an increase in inflammatory mediators.
An increase in the size and number of fat cells and fibroblasts, in conjunction with the secretion of glycosaminoglycans, leads to an expansion of the orbital volume and results in congestion of orbital structures and proptosis.
Inflammation of the extraocular muscles initially causes swelling and eventually leads to fibrosis and scarring, resulting in restrictive strabismus.
Optic neuropathy may result from compression of the optic nerve by enlarged muscles, especially when this occurs at the orbital apex.
Eyelid retraction is a complex change and may be caused by enlargement and fibrosis of the levator palpebrae superioris muscle, sympathetic overstimulation, fixation duress due to inferior rectus restriction, and possibly orbicularis oculi weakness due to muscle loss. This contributes to lagophthalmos and exposure keratopathy.

American Thyroid Association. Classification based on the first letter of the defining characteristic of each class, the classification is known as: ‘no signs or symptoms; only signs; soft tissue; proptosis; extraocular muscle; cornea; sight loss’ (NOSPECS). Furthermore, the severity of each clinical parameter in a class can be further described by a grading system of o (absent), a (minimal), b (moderate) and c (maximal).

Assessing disease activity in TED pt, using clinical assessment score (CAS), each point score 1:
Ocular pain at rest
Ocular pain upon movement
Swelling of eyelid
Redness of eyelid
Redness of conjunctiva
Chemosis of conjunctiva
Chemosis of caruncles
Increase Proptosis >/= 2mm
Decrease eye movement any direction >/= 5 degree
Decrease pinhole visual acuity >/= one line on Snellen chart

Point 3 or less indicate poor response to anti-inflammatory ( fibrosis state)
Point 4 or more: 80% respond to corticosteroid

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